


Enhancements

by BurntSushiRoll



Category: Rise of the Teenage Mutant Ninja Turtles (Cartoon 2018), Teenage Mutant Ninja Turtles - All Media Types
Genre: Angst, Brotherly Love, Gen, Hurt Leonardo (TMNT), Loss of Limbs, also this become so Leo and Donnie focused I am so sorry, anyways I HOPE YOU LIKE THIS FIC SHADOW, i just rated it teen just in case, i need to write a fic with just Raph and Mikey to make up for this, or any vivid descriptions of it, the poor boy, there's no gore or anything
Language: English
Status: Completed
Published: 2020-07-16
Updated: 2020-07-16
Packaged: 2021-03-05 03:55:00
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,729
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25297975
Author URL: https://archiveofourown.org/users/BurntSushiRoll/pseuds/BurntSushiRoll
Summary: Donnie's made plenty of inventions throughout the years; most of which he is incredibly proud of.And while this invention is not flashy, nor cool, and neither as effective as his other ones, it's the most important one he's ever made.
Relationships: Donatello & Leonardo (TMNT)
Comments: 18
Kudos: 204





	Enhancements

**Author's Note:**

  * For [OneThumpAway](https://archiveofourown.org/users/OneThumpAway/gifts).



> HAPPY BIRTHDAY SHADOW!!
> 
> This is a b-day fic for the lovely TMNTLovingLeo and I wanted to write a special something for a special someone! Ya'll should go check her out! :D

It's late in the lair; around 2 in the morning if the creek in his neck and the stiffness of his back are any indication of how long he's been bent over his worktable. Despite the bags that have formed beneath his eyes and the consistent yawning, Donnie finds himself still glued to the work at hand.

His only company at this hour is the quiet strum of classical music, drowning out the sounds of his whirring computers and the tapping of his stylus to his tablet. He works best with the accompaniment of music, but the stillness of the lair tells him that it'd be a mistake to play his usual choice of beats, so he settled for classical, his next choice of preference. 

The light from the screen, however, is beginning to bug Donnie's eyes, and as he attempts to rub the sleep from them, his eyes start to water and glisten.

He tells himself that they're from exhaustion, and nothing else. 

The past month has been the hardest month Donnie has probably ever been through. He thought that as time went on, the events wouldn’t haunt him as much; that if he kept busy with this project, he'd distract himself from the emotions and fears that hover above his conscience. 

Looking back to the tablet, Donnie looks over the blueprint once again, checking for flaws and design errors he might have missed.

He didn't tell anyone he was making this.

He figures he should have; it's kind of a big thing to keep hidden from his family, especially since it could forever change the course of his brother’s life. 

But Donnie knows that the worst thing he could do right now was to give them false hope. He knows that while science is his passion and he's really good at it, sometimes there are limits to even what science can do.

That doesn't stop him from trying though; from researching the nervous system to understanding how brain signals function, Donnie has worked tirelessly day and night.

He just has to succeed what modern medical science has not. No biggie.

Pushing the end of the stylus to his chin, Donnie leans back in his chair, staring at the ceiling like it has all the answers to his questions. 

This whole mess has left his head reeling. Donnie isn't one to dwell on things (he absolutely is) but ever since the "Incident" Donnie has done nothing but lock himself in his lab, ignoring his emotions and Mikey and Raph’s voiced concerns by focusing on his new project.

Well, he's not gonna get anywhere staring off. 

So he raises from his chair, stretching his arms above his head while leaning backwards to pop his tortured spine, and grabs his tablet, leaving for his brother’s room. Leo's room is dark. Standing in the doorway, Donnie feels and looks like an awkward weirdo. He was not the only brother to lock himself away. At first, it was because Leo was unconscious and healing from his wounds. For the better half of a week, Leo would not wake up, lost in the waves of sleep and only one brother had been allowed in his room at a time. 

He’s still in the process of healing, but even though Splinter had declared Leo was well enough to at last leave his room, Leo hasn’t taken up the offer besides to go get something to eat or use the bathroom, limping back to hide in his room and avoiding them.

In a sense, they know he's in a state of grief. For one of them, descendants from a long line of ninjas, to lose one of their-

Sighing, Donnie enters the bedroom, despite how the distance from the doorway to the bedside had seemed like miles wide, looming before him with the weight of the situation.

Sitting down on the edge of the bed, Donnie leans over to gently shake his sleeping brother’s shoulder, having to move through his covers as Leo is currently snuggled deep beneath a mountain of blankets. 

Leo groggily stirs. Rolling over to face his older brother, Donnie winces at the exhaustion pulling at his Leo’s face, the bags, visible with his mask off, beneath his eyes giving Donnie’s a run for their money. 

“What?” he asks, his voice thick with sleep and a smidge of irritation at being woken up.

Donnie doesn’t answer right away. He stares at his tablet, trying to find the right words. He hears the rustling of fabric as Leo struggles to a sitting position. Neither one talks for a moment, waiting for the other to speak up. When the silence drags on for a bit too long, it’s Leo who breaks it.

“Hey, Dee, what’s up?” Leo asks again. Donnie has never been good at hiding what he’s feeling from his face. It doesn’t help that Leo has a knack for being able to tell what his brothers are feeling, regardless of how well they thought they hid it.

Donnie takes a deep sigh, before saying, “I just needed to talk about something, and I, uh, need your opinion on something.”

“Well, can it uhhh, wait till morning?” Leo asks. 

Donnie’s eyebrow twitches. He can't just outright say it; he might be blunt but he knows this is a more delicate topic.

“This is serious, Leo."

Leo raises his eyebrows in slight shock, and he must feel slightly guilty for trying to turn his brother away by the way he rubs at his neck with his arm, his one arm-

Donnie looks away again, feeling sick all of a sudden. He shouldn’t have come. His brother is still severely injured, and he's keeping him awake from his overdue sleep, and this whole thing should've never happened. 

“Hey, what is it? Your face turned all silly-lookin'."

Donnie whirls around angrily, shooting a heated glare at his brother. He shouldn't be letting his anger out on his wounded brother, but he can't stop the hurt he felt.

Leo, shocked at the response, quickly says, "Woah, sorry. I was just trying to lighten the mood. There's not much I can do now anyways; my remarks are all I have."

Donnie shakes his head, “That’s not true, ‘Nardo. We've been over this; you're always our brother, no matter if you can't fight anymore.”

He turns on his tablet, analyzing the blueprint on screen, before continuing, “But… I might be able to help with that, actually.”

At that, Leo brightens up considerably, hope and just a tad bit of desperation coloring his eyes, but he stays quiet, wanting Donnie to continue before getting ahead of himself.

Donnie takes it as his cue to hold up the tablet for Leo to see, displaying the blueprint.

“Is that… a robot arm?!”

Donnie rolls his eyes.

“No, it’s not. Well… ok yes, in a way, it is a robot arm. But, it’s a cybernetic prosthetic that I designed with your specific dimensions. It’s in the early stages so I can't guarantee it'll work, however…”

“Are you saying… that I can have my arm back?”

Donnie grasps his own bicep with his hand.

“I don’t know. There’s still so much to do, Leo, and just because I have it planned doesn't mean it'll actually work. It’s not like my situation where I can create battle shells for my soft shell. It might not even work.”

“Oh… well have you told the others, yet?”

“I didn’t want to get their hopes up. I only went to you cause, well… at the end of the day, it is your choice.”

Donnie searches Leo's face, waiting for the disappointment to settle in. It never does, even when his face stays grim.

Leo nods slowly, face pensive. He gestures for the tablet, which Donnie hands over. Setting it in his lap and using his hand, he zooms in and out, looking over all the different angles the cybernetic arm.

A small smile creeps at Leo’s lips, “Think you can add some stripes to it?”

Donnie copies the smile, if a bit more smug, “Oh please, a paint job is basically child’s play to what I have planned for that arm.”

Leo nods with determination. 

“Then let's do it.” Even with Leo's faith behind him, it still takes Donnie a while before he has a working prototype ready for testing. Technology and biology are definitely his strong suits, but figuring out how they work together is a different challenge altogether. 

Some prototypes ended up lighting on fire. Donnie doesn't know how it kept happening, but Leo always laughed it off whenever he visited the lab, checking up on Donnie's progress.

If that's the one positive that has come out of this whole mess, it was that Leo finally regained some form of his older self. Whenever he's not in the lab or sleeping in his room, he'll join Mikey in the arcade (it's hard to play any kind of video game with only one limb, but he's still got two legs so dancing games are still available) or let Raph mother-hen him with a small smirk.

Seeing his brother acting like how he should be further fuels Donnie in his mission. At this point, failure is not an option.

After one long night of tediously fusing together a network of wires, learning from past mistakes and using a more enhanced metal casing, Donnie finally had a working prototype. 

Which led everyone to Donnie's lab, excited with nervous anticipation. Leo sits on the worktable, legs swinging back and forth anxiously, trying to appear nonchalant but failing miserably. Mikey sits next to him, letting Leo lean against him for support. 

"It won't be painful, will it?" Raph asks, hovering above Donnie’s shoulder, worrying his bottom lip with his snaggletooth. 

"No, Raph, I'm only checking the reaction speed of the arm in time with Leo's brain signals. I'm not actually attaching the arm; I have to make sure everything's all green before I proceed any further," Donnie explains, twisting the prosthetic in his hold.

Raph responds by pressing his fingers together.

"Come on, Don, some of us have places to be," Leo says. 

Donnie doesn't mention the slight shake to Leo's voice when he replies, "Hush it. Test subjects don't speak during testing."

As he stands before Leo, Donnie motions for Mikey to move, which he does so in a swift jump. 

"Ready?"

Leo laughs, even as sweat beads down the side of his head.

"Born ready."

Donnie wastes no more time. He positions a temporary clamp attached to the prosthetic to Leo's shoulder, careful as to avoid the sensitive and still healing tissue. 

Once, settled in position, Donnie takes his wrist tech and brings up on his small screen a batch of coding.

"I'll sync the arm to the chip, so give me a second."

"Chip?"

Donnie grabs a small circular device, donut-shaped and glowing a bright tone of blue, holding up for Leo to clearly see it.

"This. This little guy is gonna be the one sending encrypted coding to the prosthetic, translating your brain waves into code and then taking that code and turning it into movements."

Once the synchronization is complete, Donnie adheres the chip to the side of Leo's temple. It blinks once, then twice before steadying and remaining consistent.

"Well, everything's ready. Go ahead and try to move the arm."

Leo takes a deep breath as he closes his eyes. When he opens them, he stares at the robotic hand and wills the fingers to move.

The room is thick with silence, building and building as the seconds whisk by. 

Nothing moves. Leo furrows his brow further, his whole forehead breaking out with sweat at the heavy concentration. He's too busy willing the hand to move he doesn't notice the looks of apprehension from his brothers.

When the seconds have turned into minutes, Donnie looks to his wrist to view what went wrong.

Leo lets out his held breath, as well as a frustrated groan.

"Why won't it work?!"

"Give me a sec, Leon, there's probably just a strand of code I missed."

Leo sighs deeply, his body starting to feel both really heavy and light at the same time. His mind is slightly foggy, the corners of his vision dark and muddy.

He'll be like this forever. His brothers will continue to be heroes, fighting villains side by side while Leo remains left behind. Even if he learned to fight with only one arm, by the time he learned his brothers would be too far to catch up to.

He squeezes his eyes shut to prevent tears from streaming down his face, and he clenches his fists.

A muffled gasp echoes in the silence.

"Leo!"

As he looks down at his arm, he sees his clenched fists, two clenched fists-

Startled, but happy, tears spring from his eyes as Leo giggles with unbridled joy. His brothers grab him in an enormous hug, matching tear tracts staining their faces. As if a bubble has burst, the dark atmosphere raining above the brothers shrinks away. Months later, Leo slowly gains more and more mobility with his new prosthetic. As promised, Donnie and Mikey deck out the new arm with tons of stripes, some even shaped like lightning bolts. The base color is a dark royal blue, with the stripes being red, purple, and orange respectively. 

The first month is the adjustment period. After attaching the prosthetic properly, Leo practices reusing his arm and reworking his muscle memory. It was common for Leo to squeeze too tightly or with not enough pressure, with cups and mugs breaking or being dropped. Without the sensation of touch, Leo went through a learning curve of how to even function like a normal person again.

Sword training was even more difficult. Leo would all too often find himself switching his grip in the middle of practice when all of a sudden his sword slipped from his prosthetic and into the opposite wall.

Learning's difficult, and more often than not Leo gets so frustrated he has to go for a run, but Leo's never been more grateful for the opportunity to even have the option.

After a particularly hard day, Leo lays on the top of a skyscraper, shell pressed against concrete as he fights to get his breath under control. The run had helped to clear his mind, but his legs shook from exertion, so he decides to wait before heading back home. 

He's not alone for too long, hearing the whirring of a motor and scaly feet slapping on cold concrete.

"Did you have fun?"

Leo smiles, spreading out his limbs in a wide stretch. 

"Yep."

Donnie sits next to him, watching with intent eyes glued on his prosthetic. 

"It's fine, Dee, it's not bothering me anymore."

Donnie raises an eyebrow. 

"Are we talking about the physical discomfort it was causing earlier or about something else?"

Leo lets out a sigh. 

"I'm fine," at Donnie's exasperated face, he quickly adds, "Honestly! I'm good, it's just… hard is all."

"...Yeah?"

It's right there, on top of a New York City building, that Leo finally breaks down. Heavy sobs rack his body, thick tears slide down his face, and he hides his face in his hands. He cries then, and he continues to cry even as Donnie pulls him up by his shoulders and envelopes him in a tight hug. Leo clutches at his battle shell, crying into his older brother's shoulder. 

It's not until his sobs slowly die down that they separate, Leo furiously wiping at his wet eyes while Donnie thumbs away his own. 

"Sorry I- _hic_ -don't know where that came from."

"It's, uh, ok."

Donnie clears his throat.

"Do you, you know, wanna talk about it, maybe?"

Leo shakes his head, holding his metal hand in his flesh one, feeling the grooves and indents, memorizing every inch of it.

He smiles, so wide and bright it could blind even those who can't see.

"No, I just wanna say thanks," Leo says. "Thank you, Donnie."

And Donnie would say with much pride that he's proud of his inventions. Not all of them are flashy, or cool, or even effective at times, but any invention that can bring back his brother's happiness is worthwhile is his opinion. 

It's the most important invention Donnie has ever made.

"You're very welcome, 'Nardo."

**Author's Note:**

> :-)
> 
> she said she wanted the angst


End file.
